/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: ${USER}
 * Date: ${YEAR}-${MONTH}-${DAY}
 * Time: ${TIME}
 */
public class Main {
    public static void main(String[] args) {
        int flag = 1;
        double sum = 0;
        for (double i = 1; i <= 100 ; i++) {
            sum += 1/i*flag;
            flag = -flag;
        }
        System.out.println(sum);
    }
}